(1) Field of the Invention
The invention relates to apparatus for treating liquids and is directed more particularly to apparatus for acoustically removing gases dissolved or entrained in viscous liquids, such as oils.
(2) Description of the Prior Art
Acoustically removing gases from liquids generally is known in the art. U.S. Pat. No. 3,853,500, issued Dec. 10, 1974 to Hans-Ulrich Gassmann, et al, discloses an apparatus for degassing viscous liquids, the apparatus including a gas tight vessel, means for conveying the viscous liquid from a holding tank to the vessel, ultrasonic oscillators fixed to the outer side wall of the tank, a vacuum pump for maintaining a vacuum in the tank above the level of the liquid, and conduit and pump means for drawing liquid out of the tank.
U.S. Pat. No. 3,904,392, issued Sep. 9, 1975 to Jack A. Vaningen discloses a similar apparatus, but having an ultrasonic transducer fixed to an outer bottom wall of the vessel, the transducer having fixed thereto an ultrasonic horn which protrudes into the vessel from the bottom of the vessel. U.S. Pat. No. 4,070,167, issued Jan. 24, 1978 to Eugene H. Barbee, et al, discloses an apparatus generally similar to the '392 apparatus and having an ultrasonic transducer fixed to the bottom of a well depending from the bottom of the vessel, and a horn extending through the bottom of the well, into the well and into the vessel. In Vaningen and Barbee, the horn imparts acoustic energy to the liquid.
In the systems disclosed in the above-referenced patents, the vessels are sealed and receive liquid conveyed thereto from a holding tank. The systems further include means for pumping the degassed liquid from the vessel to a point of use. The systems generally are permanent installations requiring a substantial area and requiring supporting machinery.
It is deemed beneficial to have available means for degassing small amounts of oil. In military applications it often is necessary to add to an apparatus such as a transformer, or a weapon, or an underwater acoustic device, liquids such as transformer oil, castor oil and silicone oil. The amounts of oil involved are relatively small. It is desirable to remove gases from the oils before introducing them into the apparatus. However, an extensive space-consuming system for degassing is not practical.
Further, attaching an ultrasonic transducer to a wall of a vessel results in part of the acoustic energy of the transducer passing through the walls, resulting in noises radiating from the vessel walls. In military applications, it is at times imperative that radiated noise be at a minimum. It therefore is deemed advantageous to provide a degassing operation which not only is adapted to handle small quantities of liquid in a limited space, but which also includes a transducer separated from the walls, top and bottom of the vessel to reduce radiated noise from the vessel.